Some electronic systems enable a computer user to view on his display images that are generated on another computer remotely located from his computer. In some such systems, graphical data generated on the remotely located computer is transmitted to the user's computer, accompanied by one or more commands. The commands cause the user's computer to modify the user's display based on the graphical data. Various data compression techniques are used to enhance the transmission efficiency of the graphical data. However, many of these techniques contain inherent problems that maintain transmission efficiency at undesirably low levels.